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Just about to retire the 7800 group and move onto Dura Ace 11.The dilemma I have now is what to do on the PM front.I am currently on a P2M Rotor 3d. This has been superb, never missed a beat in 18 months. I would really like to maintain the groupset continuity with the new group and use the 9000 cranks with the stages PM.

Pros & Cons as I see them:

Rotor: I have a 34/50 and 36/52 set up already,so have all terrains covered.P2M has been great. If the stages is as reliable, don't think I will miss the L/R measurement.Also, as much as I like, or do not find a down side to, the Q rings, I am not too sure I would miss them.Downside on the rings is they are pain to change with the P2M, the crank must be removed from the spider to replace the big ring.

9000: this will maintain the aesthetic and with the stages PM, will be lighter. Also easier to move the LH crank between other bikes and change rings. I know too that the front mech change will also be improved.

On the downside, the rings I believe are very expensive, but if I get the 52/36, I think an extra 34 would cover all I need. Lastly the stages is an unknown to me, but I have read some good reviews.

So, if anyone out there has any useful advice, and especially anyone who has gone from P2M to Stages, I would love to read your opinions. Thanks

I went from a Powertap -> Quarq -> Stages over the course of the past 10 years or so.

I haven't had any major complaints with the Stages yet and I've been riding it since January and in all weather. I will say that it's a bit slower on the pickup. That said, it seems to compensate for this by extending the reading a bit so I guess it's a wash. For most of my training it's a fine device that gets the job done.

I like that it can zero itself automatically without stopping and that it has temperature compensation. In addition the iPhone app is tremendously useful in diagnostics and firmware updates. So all things considered I'm completely happy with the Stages and would recommend it to anyone on Shimano who wants to maintain the aesthetic and preserve the best shifting around. Plus- their customer service is spectacular and that matters a lot when you're dropping coin on a toy.

Like any powermeter- when you switch devices you'll have to recalibrate your training. That is, on a high-reading powertap my FTP may be 350. On a Quarq it may be 330 and on a Stages it may be 320. This is only problematic if you're constantly switching PMs. If you stay on one unit, test on that unit and consistently use that unit then you'll be fine.

How much would you be spending? the advantages seem pretty minimal for what is likely a large dollar cost.

if you already have a 110BCD rotor, going to the new4 bolt shimano system seems abit pointless to me. you can go any chainring comboyou want with a 110BCD that the shimano 4 bolt offers, and you wouldn't be locked in to expensive ( albeit good) shimano chainrings.

Thanks for the replies guys. I have thought long and hard and decided to stick with the rotor. As pointed out, the shimano chain rings are very expensive, as too are Q rings. The factor that swings it for me is that it is so easy to pick up lightly used Q rings that I don't think I would ever have to buy a new chainring again. Decided to by the complete Dura Ace group and I will sell off the chainset.

I've seen fairly good consistency on left right balance on Vector when I plot it versus power, but it changes with power. So in going to Stages I'd lose linearity...2x measured power isn't 2x actual. But at a given power the error for me would be relatively consistent.

That said I care enough about data integrity I'd forget aesthetics and stick with power2max.